Table 310.64 Thickness of Insulation for Shielded Solid Dielectric Insulated Conductors Rated 2001 to 35,000 Volts
| Conductor Size (AWG or kcmil) | 2001 - 5000 Volts | 5001 - 8000 Volts | 8001 - 15,000 Volts | 15,001 - 25,000 Volts | 25,001 - 28,000 Volts | 28,001 - 35,000 Volts | ||||||||||||||||
| 100 Percent Insulation Level 1 | 133 Percent Insulation Level 2 | 100 Percent Insulation Level 1 | 133 Percent Insulation Level 2 | 100 Percent Insulation Level 1 | 133 Percent Insulation Level 2 | 100 Percent Insulation Level 1 | 133 Percent Insulation Level 2 | 100 Percent Insulation Level 1 | 133 Percent Insulation Level 2 | |||||||||||||
| mm | mils | mm | mils | mm | mils | mm | mils | mm | mils | mm | mils | mm | mils | mm | mils | mm | mils | mm | mils | mm | mils | |
| 8 | 2.29 | 90 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| 6-4 | 2.29 | 90 | 2.92 | 115 | 3.56 | 140 | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – |
| 2 | 2.29 | 90 | 2.92 | 115 | 3.56 | 140 | 4.45 | 175 | 5.46 | 215 | – | – | – | – | – | – | – | – | – | – | – | – |
| 1 | 2.29 | 90 | 2.92 | 115 | 3.56 | 140 | 4.45 | 175 | 5.46 | 215 | 6.60 | 260 | 8.76 | 345 | 7.11 | 280 | 8.76 | 345 | – | – | – | – |
| 1/0- 2000 |
2.29 | 90 | 2.92 | 115 | 3.56 | 140 | 4.45 | 175 | 5.46 | 215 | 6.60 | 260 | 8.76 | 345 | 7.11 | 280 | 8.76 | 345 | 8.76 | 345 | 10.67 | 420 |
1 100 Percent Insulation Level. Cables in this category shall be permitted to be applied where the system is provided with relay protection such that ground faults will be cleared as rapidly as possible but, in any case, within 1 minute. While these cables are applicable to the great majority of cable installations that are on grounded systems, they shall be permitted to be used also on other systems for which the application of cables is acceptable, provided the above clearing requirements are met in completely de-energizing the faulted section.
2 133 Percent Insulation Level. This insulation level corresponds to that formerly designated for ungrounded systems. Cables in this category shall be permitted to be applied in situations where the clearing time requirements of the 100 percent level category cannot be met and yet there is adequate assurance that the faulted section will be de-energized in a time not exceeding 1 hour. Also, they shall be permitted to be used where additional insulation strength over the 100 percent level category is desirable.